Yamaha MX775 - CHECKING THE ARMATURE COIL

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ELECTRICAL
ELECTRIC STARTING SYSTEM
CHECKING THE ARMATURE COIL
1. Check:
• Commutator (outer surface)
Dirty  Clean it with #600 grit sandpaper.
2. Measure:
• Mica (insulation depth between the commutator
segments)
Out of specification  Scrape the mica to the
proper measurement using a hacksaw blade which
has been grounded to fit the commutator.
TIP
The mica insulation of the commutator must be undercut to
ensure proper operation of the commutator.
3. Measure:
• Armature coil (insulation/continuity)
Defects  Replace the starter motor.
Connect the digital circuit tester to the armature
coil.
a
Depth of insulator “a”:
2.0 mm (0.79 in)
Model 88 Multimeter with tachometer:
YU-A1927
Commutator continuity:
Continuity
Insulation resistance:
More than 1.0 M
3
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1. Continuity check
2. Insulation check
3. Armature coil